Development of Expansive-High Strength Concrete and Systematic Evaluation of Structural Behavior of Reinforced Concrete Beams

膨胀高强混凝土的开发及钢筋混凝土梁结构性能的系统评价

• 批准号: 16360220
• 负责人: SATO Ryoichi
• 金额: $ 8.83万
• 依托单位: Hiroshima University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-16360220/
• 关键词: Expansive-high strength concrete; Autogenous shrinkage; Reinforced concrete; Flexural crack width; Micro cracking; Curvature; Shear strength; 長期曲けひび割れ幅; 長期変形; 寸法効果; クリープ解析; せん断補強筋応力; Expansive-high strength concrete; Autogenous shrinkage; Reinforced concrete; Flexural crack width; Micro cracking; Curvature; Shear strength; 長期曲けひび割れ幅; 長期変形; 寸法効果; クリープ解析; せん断補強筋応力

Expansive-high strength concrete(E-LAS) with compressive strength over 100N/mm^2 and expansive strain reaching 200 X 10^<-8> at maximum was developed, which was made of low heat Portland cement, expansive additive and shrinkage reducing agent.Stress produced in E-LAS ranged from 0.5 to・.2 N/mm2, which was not strongly dependent on the strain.The ultimate and rate of creep strains of E-LAS and conventional HSC(N-HAS) obtained experimentally showed less difference between both concretes for the case of with water to binder ratios(W/B) of 0.3. Linear creep analysis based on step by step for reinforced HSC beams showed fairly good agreement with experimental results, while the former overestimated shrinkage stress and underestimate expansive stress of HSC with W/B of 0.15 with the increase of RB ratio. The reason for the overestimate of shrinkage stress was explained by the detection of micro cracking developed in the radial direction and the computed result was improved by incorporating t … More ension softening of concrete depending on the age.Effectiveness of E-LAS was verified by experiment for improving the serviceability performance of short-and long-term flexural crack width as well as curvature of reinforced concrete(RC) beams and a new concept was proposed for evaluating them based on the strain change in tension RB from the zero concrete stress condition at tension RB depth to the loaded condition and the change of stress related curvature before and after loading, respectively, whose validity was verified by comparing with results obtained by conventional method and experiment, while tension softening effect must be considered in case of small crack width.Shear strength at diagonal cracking of E-LAS beams, whose effective depth(d) is from 250-1000mm and strain in tension RB before loading is almost zero, was improved by 5% for d=250mm, 12% for d=500mm and 19% for d=1000mm, compared with that of N-HAS beams with remarkable shrinkage strain in the same RB. A concept of equivalent tension RB ratio considering RB strain due to early age deformation was proposed. The concept showed the linear relationship between shear strength at diagonal cracking and (effective depth)^<-1/3> independent of early age deformation, while previouisly proposed equations followed the law of (effective depth)^<-1/2> and (effective depth)^<-2/5> for RC beams made of N-HAS. A proposed equation formulated based on this concept showed high prediction accuracy independent of the magnitude of early age deformation in concrete.E-LAS was also effective in improving shear strength of RC beams which was 13% for shear RB ratio of 0.25% and 6% for 0.51% higher than that of corresponding N-HAS beam, respectively. The shear RB strains averaged along a primary shear crack of E-LAS beams were smaller than those of N-HAS beams which could be roughly predicted by the modified truss theory applied a proposed equation for evaluating concrete contribution for shear resistance. Less

开发了膨胀高强度混凝土（E-LAS），具有超过100n/mm^2的抗压强度和最大达到200 x 10^<-8>的额外压力，开发了由低热的波特兰水泥制成的，广泛的添加剂和收缩剂的降低剂。在E-LAS中产生的压力范围为0.5至0.5至.2 n/mm2，并且在cr的范围内，频繁的频率不超过，并且在cr频范围内，频繁的频率是频繁的。传统的HSC（N-HAS）在实验上显示出两种混凝土的差异较小，而水与粘合剂比（w/b）为0.3。基于加强HSC梁的逐步分析的线性蠕变分析与实验结果表现出相当良好的一致性，而前者高估的收缩应力和RB比率的增加，低估HSC的广泛应力，w/b为0.15。通过在径向方向上发现的微裂纹的检测来解释高估了高估压力的原因，并通过结合t进行了改善，根据t…更多地根据年龄的变化来改善混凝土的降温。通过实验，E-LAS的效果得到了验证。根据张力RB的应变Rb的应变变化对张力RB深度的应变变化到负载和压力相关的曲率的变化，分别在加载前后的压力相关曲率的变化，其有效性是通过与常规方法和实验获得的结果进行比较，而在小裂纹的情况下必须考虑到e g裂纹的效果，diag的强度（diagneah e e dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia dia）加载前的250-1000mm和张力RB的应变几乎为零，D = 250mm的5％提高了5％，D = 500mm的12％，D = 1000mm的19％，与N-HAS束相比，在同一RB中具有明显的收缩应变。考虑了由于早期变形引起的RB菌株的等效张力RB比的概念。该概念显示了对角裂纹处的剪切强度与（有效深度）^<-1/3>独立于幼年变形的线性关系，而先前提议的公益遵循（有效深度）^<-1/2>的定律和（有效的深度）^<-2/5>对于由N-HAS制成的RC束。基于此概念形成的提出的方程式，表明高预测精度与混凝土中早期变形的大小无关。E-LAS也有效地提高了RC梁的剪切强度，剪切RB比分别为0.25％和6％的剪切强度为13％，分别比相应的N-HAS束高0.51％。沿E-LAS梁的一级剪切裂纹平均的剪切RB应变小于N-HAS梁的剪切菌株，而N-HAS梁的剪切菌株可以通过修饰的桁架理论大致预测的N-HAS束的剪切率施加了一个提议的方程式，以评估剪切电阻的混凝土贡献。较少的